Description:
Sodium Ascorbate Crystals Supports Immune System Sodium ascorbate
is non-acidic (pH neutral), making it gentle on the digestive system. It provides the sodium necessary to carry out the active absorption of ascorbic acid. Vitamin C plays a vital role in ...

Ask A Question

Customer Reviews

Health Notes

Disclaimer:
This scientific independent research is provided by Aisle7 and is for informational use only. GNC provides this information as a service but does not endorse it. Likewise, Aisle7 does not recommend or endorse any specific products.

For an herb, supported by traditional use but minimal or no scientific evidence. For a supplement, little scientific support.

Our proprietary "Star-Rating" system was developed to help you easily understand the amount of scientific support behind each supplement in relation to a specific health condition. While there is no way to predict whether a vitamin, mineral, or herb will successfully treat or prevent associated health conditions, our unique ratings tell you how well these supplements are understood by the medical community, and whether studies have found them to be effective for other people.

For over a decade, our team has combed through thousands of research articles published in reputable journals. To help you make educated decisions, and to better understand controversial or confusing supplements, our medical experts have digested the science into these three easy-to-follow ratings. We hope this provides you with a helpful resource to make informed decisions towards your health and well-being.

This supplement has been used in connection with the following health conditions:

Dose: 1 to 4 grams dailyStudies have shown that taking vitamin C may make your cold shorter and less severe.(more)

Infection

Dose: 1 to 4 grams dailyVitamin C has antiviral activity, and may help prevent viral infections or, in the case of the common cold, reduce the severity and duration of an infection.(more)

Bronchitis

Dose: 200 mg dailyIn a double-blind study of elderly patients hospitalized with acute bronchitis, those given vitamin C improved to a significantly greater extent than those who were given a placebo.
(more)

Dose: Consult a qualified healthcare practitionerVitamin C stimulates the immune system. While taking it has only a small effect in preventing colds, it does significantly reduce the duration of a cold when taken at the onset.(more)

Dose: 200 mg with 200 mg flavonoids, three to five times dailyVitamin C plus flavonoids may help speed cold sore healing.
(more)

Pre- and Post-Surgery Health and Vitamin C Deficiency

Dose: 100 to 250 mg once or twice per dayVitamin C supports immune function and is a critical nutrient for wound healing. Supplementing with it may decrease the risk of excessive bleeding in the surgical setting.(more)

Dose: Refer to label instructionsSome doctors recommend that people with hypertension supplement with vitamin C, which has been found to have a blood pressure–lowering effect.(more)

Heart Attack

Dose: Refer to label instructionsVitamin C has been reported to protect blood vessels from problems associated with heart attack risk in a variety of ways.(more)

Chronic Obstructive Pulmonary Disease

Dose: Refer to label instructionsIn one study, people who got more vitamin C from their diet were less likely to be diagnosed with bronchitis, however, vitamin C has not been studied in relation to COPD.(more)

Heart Attack and Vitamin C Deficiency

Dose: 100 to 200 mg dailyTaking vitamin C may reduce heart attack risk in people who are deficient.(more)

Dose: 750 mg dailyVitamin C has been shown to improve fertility in woman with a uterine condition known as luteal phase defect.(more)

Menopause

Dose: Refer to label instructionsA combination of vitamin C and the flavonoid hesperidin were reported to relieve hot flashes in menopausal women.(more)

Menorrhagia

Dose: Refer to label instructionsVitamin C protects capillaries (small blood vessels) from damage. In so doing, it might protect against the blood loss of menorrhagia.(more)

Amenorrhea

Dose: Refer to label instructionsVitamin C combined with the drug clomiphene, which affects female hormone levels, is more effective at stimulating ovulation in women with amenorrhea than either substance alone. (more)

Dose: 500 mg twice per daySupplementing with vitamin C may benefit people with type 1 diabetes in several ways, including by reducing sorbitol levels, urinary protein loss, glycosylation, and eye damage.(more)

Dose: Refer to label instructionsVitamin C helps control blood sugar levels in people with diabetes, and since there are similarities in the way the body regulates high and low blood sugar levels, it might be helpful for hypoglycemia as well.(more)

Dose: Refer to label instructionsVitamin C combined with the drug clomiphene, which affects female hormone levels, is more effective at stimulating ovulation in women with amenorrhea than either substance alone. (more)

Dose: 1 gram per 20 lbs (9 kg) body weight per day
In one trial, autistic children given vitamin C had less severe symptoms than those taking placebo, possibly because vitamin C affects a hormone pathway typically disturbed in children with autism.(more)

Childhood Diseases

Dose: Refer to label instructionsVitamin C enhances the immune system and may protect against viral infections, including measles and chicken pox.(more)

Ear Infections

Dose: Refer to label instructionsSupplementing with vitamin C stimulates the immune system and may help prevent ear infections.(more)

Dose: Consult a qualified healthcare practitionerPeople with schizophrenia may require more vitamin C than the general population. In one trial, vitamin C reduced hallucinations, suspiciousness, and disorganized thoughts.(more)

Age-Related Cognitive Decline

Dose: Refer to label instructionsUse of vitamin C, alone or with vitamin E, has been associated with better cognitive function and a reduced risk of certain forms of dementia (not including Alzheimer's disease).(more)

Bipolar Disorder

Dose: Refer to label instructionsVitamin C helps the body reduce its load of vanadium, a mineral that adversely influences bipolar disorder. It has improved symptoms of depression and mania in some studies.(more)

Dose: 400 mg daily for several days before and after intense exerciseTaking vitamin C for several days before and after intense exercise may reduce pain and speed muscle strength recovery.(more)

Athletic Performance and Vitamin C Deficiency

Dose: If deficient: 100 to 200 mg dailyAntioxidants, including vitamin C, neutralize exercise-related free radicals before they can damage the body, so antioxidants may aid in exercise recovery. Especially in cases of vitamin C deficiency, supplementing with the vitamin may improve exercise performance.(more)

A review of 21 controlled trials using 1 to 8 grams of vitamin C per day found that "in each of the twenty-one studies, vitamin C reduced the duration of episodes and the severity of the symptoms of the common cold by an average of 23%."1 The optimum amount of vitamin C to take for cold treatment remains in debate but may be as high as 1 to 3 grams per day, considerably more than the 120 to 200 mg per day that has been suggested as optimal intake for healthy adults. A review of 23 controlled trials found that vitamin C supplementation produces a greater benefit for children than for adults.2 The same review found that a daily amount of 2 grams or more was superior to a daily amount of 1 gram at reducing the duration of cold symptoms.

Vitamin C has antiviral activity, and may help prevent viral infections1 or, in the case of the common cold, reduce the severity and duration of an infection.2 Most studies on the common cold used 1 to 4 grams of vitamin C per day.

In a double-blind study of elderly patients hospitalized with acute bronchitis, those who were given 200 mg per day of vitamin C improved to a significantly greater extent than those who were given a placebo.1 The common cold may lead to bronchitis in susceptible people, and numerous controlled studies, some double-blind, have shown that vitamin C supplements can decrease the severity and duration of the common cold in otherwise healthy people.2

Vitamin C and vitamin E may prevent oxidative damage to the lung lipids by environmental pollution and cigarette smoke exposure. It has been suggested that amounts in excess of the RDA (recommended dietary allowance) are necessary to protect against the air pollution levels currently present in North America,3 although it is not known how much vitamin E is needed to produce that protective effect.

Most,1, 2 but not all,3 double-blind studies have shown that elderly people have better immune function and reduced infection rates when taking a multiple vitamin-mineral formula. In one double-blind trial, supplements of 100 mcg per day of selenium and 20 mg per day of zinc, with or without additional vitamin C, vitamin E, and beta-carotene, reduced infections in elderly people, though vitamins without minerals had no effect.4 Burn victims have also experienced fewer infections after receiving trace mineral supplements in double-blind research.5 These studies suggest that trace minerals may be the most important micronutrients for enhancing immunity and preventing infections in the elderly.

Vitamin C stimulates the immune system by both elevating interferon levels6 and enhancing the activity of certain immune cells.7, 8 Two studies came to opposite conclusions about the ability of vitamin C to improve immune function in the elderly,9, 10 and two other studies did not agree on whether vitamin C could protect people from hepatitis.11, 12 However, a review of 20 double-blind studies concluded that while several grams of vitamin C per day has only a small effect in preventing colds, when taken at the onset of a cold, it does significantly reduce the duration of a cold.13 In controlled reports studying people doing heavy exercise, cold frequency was reduced an average of 50% with vitamin C supplements ranging from 600 to 1,000 mg per day.14 Thus, the overall effect of vitamin C on immune function is unclear, and its usefulness may vary according to the situation.

A combination of antioxidants vitamin A, vitamin C, and vitamin E significantly improved immune cell number and activity compared with placebo in a group of hospitalized elderly people.15 Daily intake of a 1,000 mg vitamin C plus 200 IU vitamin E for four months improved several measures of immune function in a preliminary study.16 To what extent immune-boosting combinations of antioxidants actually reduce the risk of infection remains unknown.

Dockworkers given 100 mg of vitamin C each day for ten months caught influenza 28% less often than did their coworkers not taking vitamin C. Of those who did develop the flu, the average duration of illness was 10% less in those taking vitamin C than in those not taking the vitamin.1 Other trials have reported that taking vitamin C in high amounts (2 grams every hour for 12 hours) can lead to rapid improvement of influenza infections.2, 3 Such high amounts, however, should only be used under the supervision of a healthcare professional.

Vitamin C has been shown to inactivate herpes viruses in the test tube.1 In one study, people with herpes infections received either a placebo or 200 mg of vitamin C plus 200 mg of flavonoids, each taken three to five times per day. Compared with the placebo, vitamin C and flavonoids reduced the duration of symptoms by 57%.2

Vitamin C deficiency can be detrimental to immune function in hospitalized patients,1 and one study found that half of surgery patients recovering at home had low dietary intakes of vitamin C.2 Vitamin C is also a critical nutrient for wound healing,3, 4 but studies of vitamin C supplementation have shown only minor effects on the healing of surgical wounds.5, 6 Vitamin C deficiency also can increase the risk of excessive bleeding in the surgical setting.7

Antioxidants may protect the skin from sunburn due to free radical-producing ultraviolet rays.1 Combinations of 1,000 to 2,000 IU per day of vitamin E and 2,000 to 3,000 mg per day of vitamin C, but neither given alone, have a significant protective effect against ultraviolet rays, according to double-blind studies.2, 3, 4

Oral synthetic beta-carotene alone was not found to provide effective protection when given in amounts of 15 mg per day or for only a few weeks' time in larger amounts of 60 to 90 mg per day, but it has been effective either in very large (180 mg per day) amounts or in smaller amounts (30 mg per day) in combination with topical sunscreen.5, 6, 7, 8, 9

Natural sources of beta-carotene or other carotenoids have been more consistently shown to protect against sunburn. One controlled study found that taking a supplement of natural carotenoids (almost all of which was beta-carotene) in daily amounts of 30 mg, 60 mg, and 90 mg gave progressively more protection against ultraviolet rays.10 In another controlled study, either 24 mg per day of natural beta-carotene or 24 mg per day of a carotenoid combination of equal amounts beta-carotene, lutein, and lycopene helped protect skin from ultraviolet rays.11 A preliminary study compared synthetic lycopene (10.1 mg per day), a natural tomato extract containing 9.8 mg of lycopene per day plus additional amounts of other carotenoids, and a solubilized tomato drink (designed to increase lycopene absorption) containing 8.2 mg of lycopene plus additional amounts of other carotenoids. After 12 weeks, only the two tomato-based products were shown to give significant protection against burning by ultraviolet light.12

Still other trials have tested combinations of several antioxidants. One preliminary study found that a daily combination of beta-carotene (6 mg), lycopene (6 mg), vitamin E (15 IU), and selenium for seven weeks protected against ultraviolet light.13 However, a double-blind trial of a combination of smaller amounts of several carotenoids, vitamins C and E, selenium, and proanthocyanidins did not find significant UV protection compared with placebo.14 Similarly, in a controlled trial, a combination of selenium, copper, and vitamins was found to be ineffective.15

It should be noted that while oral protection from sunburn has been demonstrated with several types of antioxidants, the degree of protection (typically less than an SPF of 2) is much less than that provided by currently available topical sunscreens. On the other hand, these modest effects will provide some added protection to skin areas where sunscreen is also used and will give a small amount of protection to sun-exposed areas where sunscreen is not applied. However, oral protection from sunburn is not instantaneous; maximum effects are not reached until these antioxidants have been used for about eight to ten weeks.16, 17

Vitamin C is needed to make collagen (connective tissue) that strengthens skin, muscles, and blood vessels and to ensure proper wound healing. Severe injury appears to increase vitamin C requirements,1 and vitamin C deficiency causes delayed healing.2 Preliminary human studies suggest that vitamin C supplementation in non-deficient people can speed healing of various types of wounds and trauma, including surgery, minor injuries, herniated intervertebral discs, and skin ulcers.3, 4 A combination of 1-3 grams per day of vitamin C and 200-900 mg per day of pantothenic acid has produced minor improvements in the strength of healing skin tissue.5, 6

Antioxidants have been studied as topical agents for protection against sunburn. Animal studies have found sunscreen-like effects from topical application of a vitamin C and vitamin E combination, and a controlled human study reported ultraviolet protection from the use of a lotion containing 0.02% to 0.05% of the selenium-containing amino acid known as selenomethionine.1, 2 The topical use of the hormone melatonin has been shown to protect human skin against ultraviolet rays in double-blind research.3, 4 A double-blind human trial tested topical vitamins C and E and melatonin, alone and in combinations, and found the highest degrees of protection from combination formulations containing 2% vitamin E, 5% vitamin C, and 1% to 2.5% melatonin.5 Other studies in which topical antioxidants were applied after ultraviolet exposure have found no benefits.6, 7

Antioxidants have been studied as topical agents for protection against sunburn. Animal studies have found sunscreen-like effects from topical application of a vitamin C and vitamin E combination, and a controlled human study reported ultraviolet protection from the use of a lotion containing 0.02% to 0.05% of the selenium-containing amino acid known as selenomethionine.1, 2 The topical use of the hormone melatonin has been shown to protect human skin against ultraviolet rays in double-blind research.3, 4 A double-blind human trial tested topical vitamins C and E and melatonin, alone and in combinations, and found the highest degrees of protection from combination formulations containing 2% vitamin E, 5% vitamin C, and 1% to 2.5% melatonin.5 Other studies in which topical antioxidants were applied after ultraviolet exposure have found no benefits.6, 7

Antioxidants such as vitamin C, vitamin E, and glutathione are depleted in healing skin tissue.1 One animal study found that vitamin E (alpha-tocopherol) applied to the skin shortened the healing time of skin ulcers.2 Another animal study reported that administration of oral vitamin E before skin lesions were introduced into the skin prevented some of the tissue damage associated with the development of pressure ulcers.3 A controlled human trial found that 400 IU of vitamin E daily improved the results of skin graft surgery for chronic venous ulcers.4 No further research has investigated the potential benefit of vitamin E for skin ulcers.

Animal research has suggested that vitamin C may help prevent skin ulcers,5 and in a preliminary study,6 elderly patients with pressure ulcers had lower blood levels of vitamin C than did ulcer-free patients. Supplementation with vitamin C (3 grams per day) increased the speed of healing of leg ulcers in patients with a blood disorder called thalassemia, according to a double-blind study.7 And while a double-blind trial of surgical patients with pressure ulcers found that supplementation with 500 mg of vitamin C twice a day accelerated ulcer healing,8 a similar double-blind trial found no difference in the effectiveness of either 20 mg per day or 1,000 mg per day of vitamin C.9

In 1989, Medical World News reported that researchers from the University of Texas found that vitamin C, at 50-75 mg per 2.2 pounds of body weight, reduced symptoms of eczema in a double-blind trial.1 In theory, vitamin C might be beneficial in treating eczema by affecting the immune system, but further research has yet to investigate any role for this vitamin in people with eczema.

Dose: Refer to label instructionsPeople with recurrent boils (furunculosis) may have defects in white blood cell function that are correctable with vitamin C supplementation. A preliminary study of people with recurrent boils and defective white blood cell function, found that 1 gram of vitamin C taken daily for four to six weeks, resulted in normalization of white blood cell function.Levy R, Shriker O, Porath A, et al. Vitamin C for the treatment of recurrent furunculosis in patients with impaired neutrophil functions. J Infect Dis 1996;173:15025. Ten of twelve people receiving vitamin C became symptom-free within one month and remained so for periods of one to three years without additional supplementation. The other two people required long-term vitamin C supplementation to prevent recurrences.

A clinical report describes the use of vitamin supplements in the treatment of vitiligo.1Folic acid and/or vitamin B12 and vitamin C levels were abnormally low in most of the 15 people studied. Supplementation with large amounts of folic acid (1-10 mg per day), along with vitamin C (1 gram per day) and intramuscular vitamin B12 injections (1,000 mcg every two weeks), produced marked repigmentation in eight people. These improvements became apparent after three months, but complete repigmentation required one to two years of continuous supplementation. In another study of people with vitiligo, oral supplementation with folic acid (10 mg per day) and vitamin B12 (2,000 mcg per day), combined with sun exposure, resulted in some repigmentation after three to six months in about half of the participants.2 This combined regimen was more effective than either vitamin supplementation or sun exposure alone.

Dose: 1,000 mg dailyVitamin C appears to protect LDL cholesterol from damage.1 In some clinical trials, cholesterol levels have fallen when people with elevated cholesterol supplement with vitamin C.2 Some studies report that decreases in total cholesterol occur specifically in LDL cholesterol.3 Doctors sometimes recommend 1 gram per day of vitamin C. A review of the disparate research concerning vitamin C and heart disease, however, has suggested that most protection against heart disease from vitamin C, is likely to occur with as little as 100 mg per day.4

Severe vitamin C deficiency (scurvy) is a well-recognized but uncommon cause of increased capillary fragility. Whether vitamin C supplementation can help capillary fragility in people who do not have scurvy is less clear. Patients undergoing dialysis may develop low levels of vitamin C,1, 2 which can lead to capillary fragility, but giving dialysis patients 50 mg of vitamin C per day had no effect on capillary fragility in one study.3 People with kidney failure and those undergoing dialysis should not supplement with more than 100 mg per day, unless supervised by a doctor.

According to preliminary studies, vitamin C may reduce capillary weakness in diabetics, who often have low blood levels of vitamin C compared to non-diabetics.4, 5 In a double-blind trial, elderly people with low vitamin C levels and capillary fragility were helped with supplementation of one gram per day of vitamin C.6

Experimentally increasing homocysteine levels in humans has led to temporary dysfunction of the cells lining blood vessels. Researchers are concerned this dysfunction may be linked to atherosclerosis and heart disease. Vitamin C has been reported in one controlled study to reverse the dysfunction caused by increases in homocysteine.1 Vitamin C also protects LDL.2

Despite the protective mechanisms attributed to vitamin C, some research has been unable to link vitamin C intake to protection against heart disease. These negative trials have mostly been conducted using people who consume 90 mg of vitamin C per day or more-a level beyond which further protection of LDL may not occur. Studies of people who eat foods containing lower amounts of vitamin C have been able to show a link between dietary vitamin C and protection from heart disease. Therefore, leading vitamin C researchers have begun to suggest that vitamin C may be important in preventing heart disease, but only up to 100-200 mg of intake per day.3 In a double-blind trial,4 supplementation with 250 mg of timed-release vitamin C twice daily for three years resulted in a 15% reduction in the progression of atherosclerosis, compared with placebo. Many doctors suggest that people take vitamin C-often 1 gram per day-despite the fact that research does not yet support levels higher than 500 mg per day.

Dose: Refer to label instructionsIn a pooled analysis of 29 randomized controlled trials, vitamin C supplementation, as compared with placebo, resulted in statistically significant reductions in systolic (average decrease, 3.84 mm Hg) and diastolic (average decrease, 1.48 mm Hg) blood pressure. Average blood pressure reductions in the studies that included only people with hypertension were 4.85 mm Hg for systolic and 1.67 mm Hg for diastolic blood pressure.1 Thus, vitamin C when given in moderate amounts (such as 500 mg per day), has a modest blood pressure-lowering effect, both in people with high blood pressure and in those with normal blood pressure.

Dose: Refer to label instructionsVitamin C has been reported to protect blood vessels from problems associated with heart attack risk in a variety of ways.1, 2, 3 However, research attempting to link vitamin C directly to protection from heart attacks has been inconsistent.4, 5 The reason for this discrepancy appears related to the amount of vitamin C intake investigated in these studies. True or marginal vitamin C deficiencies do appear to increase the risk of suffering heart attacks.6, 7 However, in trials comparing acceptable (i.e., non-deficient) vitamin C levels to even higher levels, additional vitamin C has not been protective.8 Therefore, though many doctors recommend that people at high risk for heart attack take vitamin C-often 1 gram per day-most evidence currently suggests that consuming as little as 100-200 mg of vitamin C per day from food or supplements may well be sufficient.

3. Rath M, Pauling L. Solution to the puzzle of human cardiovascular disease: Its primary cause is ascorbate deficiency leading to the deposition of lipoprotein (a) and fibrinogen/fibrin in the vascular wall. J Orthomol Med 1992;6:125-34.

A review of nutrition and lung health reported that people with a higher dietary intake of vitamin C were less likely to be diagnosed with bronchitis.1 As yet, the effects of supplementing with vitamin C in people with COPD have not been studied.

Vitamin C has been reported to protect blood vessels from problems associated with heart attack risk in a variety of ways.1, 2, 3 However, research attempting to link vitamin C directly to protection from heart attacks has been inconsistent.4, 5 The reason for this discrepancy appears related to the amount of vitamin C intake investigated in these studies. True or marginal vitamin C deficiencies do appear to increase the risk of suffering heart attacks.6, 7 However, in trials comparing acceptable (i.e., non-deficient) vitamin C levels to even higher levels, additional vitamin C has not been protective.8 Therefore, though many doctors recommend that people at high risk for heart attack take vitamin C-often 1 gram per day-most evidence currently suggests that consuming as little as 100-200 mg of vitamin C per day from food or supplements may well be sufficient.

3. Rath M, Pauling L. Solution to the puzzle of human cardiovascular disease: Its primary cause is ascorbate deficiency leading to the deposition of lipoprotein (a) and fibrinogen/fibrin in the vascular wall. J Orthomol Med 1992;6:125-34.

People who are deficient in vitamin C may be at increased risk for periodontal disease.1 When a group of people with periodontitis who normally consumed only 20-35 mg of vitamin C per day were given an additional 70 mg per day, objective improvement of periodontal tissue occurred in only six weeks.2 It makes sense for people who have a low vitamin C intake (e.g., people who eat few fruits and vegetables) to supplement with vitamin C in order to improve gingival health.

Vitamin C has been shown to inactivate herpes viruses in the test tube.1 In one study, people with herpes infections received either a placebo or 200 mg of vitamin C plus 200 mg of flavonoids, each taken three to five times per day. Compared with the placebo, vitamin C and flavonoids reduced the duration of symptoms by 57%.2

People who are deficient in vitamin C may be at increased risk for periodontal disease.1 When a group of people with periodontitis who normally consumed only 20-35 mg of vitamin C per day were given an additional 70 mg per day, objective improvement of periodontal tissue occurred in only six weeks.2 It makes sense for people who have a low vitamin C intake (e.g., people who eat few fruits and vegetables) to supplement with vitamin C in order to improve gingival health.

For people who consume adequate amounts of vitamin C in their diet, several studies have found that supplemental vitamin C has no additional therapeutic effect. Research,3 including double-blind evidence,4 shows that vitamin C fails to significantly reduce gingival inflammation in people who are not vitamin C deficient. In one study, administration of vitamin C plus flavonoids (300 mg per day of each) did improve gingival health in a group of people with gingivitis;5 there was less improvement, however, when vitamin C was given without flavonoids. Preliminary evidence has suggested that flavonoids by themselves may reduce inflammation of the gums.6

Animal studies suggest that supplementing with vitamin C can reduce blood levels of stress-related hormones and other measures of stress.1, 2, 3, 4 Controlled studies of athletes have shown that vitamin C supplementation (1,000 to 1,500 mg per day) can reduce stress hormone levels after intense exercise.5, 6 Surgery patients given 2,000 mg per day of vitamin C during the week before and after surgery had a more rapid return to normal of several stress-related hormones compared with patients not given vitamin C.7 In a double-blind trial, young adults took 3,000 mg per day of vitamin C for two weeks, then were given a psychological stress test involving public speaking and mental arithmetic.8 Compared with a placebo group, those taking vitamin C rated themselves less stressed, scored better on an anxiety questionnaire, had smaller elevations of blood pressure, and returned sooner to lower levels of an adrenal stress hormone following the stress test.

Dose: 500 mg twice a dayIn a double-blind study of Egyptian children with depression, the combination of vitamin C (500 mg twice a day) and an antidepressant drug (fluoxetine) was significantly more effective than fluoxetine alone.1

Dose: 200 mg niacin daily, 300 mg vitamin C daily, and 60 mg rutin daily througout menstrual cycle; for cramps: 100 mg niacin every two to three hoursThe niacin form of vitamin B3 has been reported to be effective in relieving menstrual cramps in 87% of a group of women taking 200 mg of niacin per day throughout the menstrual cycle.1 They then took 100 mg every two or three hours while experiencing menstrual cramps.2 In a follow-up study, this protocol was combined with 300 mg of vitamin C and 60 mg of the flavonoid rutin per day, which resulted in a 90% effectiveness for relieving menstrual cramps. Since these two preliminary studies were published many years ago, no further research has explored the relationship between niacin and dysmenorrhea. Niacin may not be effective unless taken for seven to ten days before the onset of menstrual flow.

Premature rupture of membranes (PROM) affects 10 to 20% of all pregnancies. It is an important cause of preterm delivery and is associated with increased rates of complications in both the mother and child. In a double-blind study, supplementing with 100 mg of vitamin C per day, beginning in the twentieth week of pregnancy, reduced the incidence of PROM by 74%.1 The women in this study were consuming only about 65 mg of vitamin C per day in their diet, which is less than the RDA of 80 to 85 mg per day for pregnant women. In a double-blind study of pregnant smokers, supplementation with 500 mg per day of vitamin C, beginning at 23 weeks of pregnancy or earlier and continuing until delivery, improved lung function and decreased the incidence of wheezing in the offspring.2

Dose: 1,000 mg vitamin C and 1,200 IU vitamin E dailyIn a double-blind study of women with pelvic pain presumed to be due to endometriosis, supplementation with vitamin E (1,200 IU per day) and vitamin C (1,000 mg per day) for eight weeks resulted in an improvement of pain in 43% of women, whereas none of the women receiving a placebo reported pain relief.1

In some women, infertility is due to a hormonal abnormality known as luteal phase defect. In this condition, the uterine lining does not develop and mature properly, presumably because of a deficiency of the hormone progesterone. In a study of infertile women with luteal phase defect, supplementation with 750 mg of vitamin C per day for up to six months resulted in a pregnancy rate of 25%, compared with a rate of 11% in an untreated control group, a statistically significant difference.1

In 1964, a preliminary trial reported that 1,200 mg each of vitamin C and the flavonoid hesperidin taken over the course of the day helped relieve hot flashes.1 Although placebo effects are strong in women with hot flashes, other treatments used in that trial failed to act as effectively as the flavonoid/vitamin C combination. Since then, researchers have not explored the effects of flavonoids or vitamin C in women with menopausal symptoms.

Both vitamin C and flavonoids protect capillaries (small blood vessels) from damage. In so doing, they might protect against the blood loss of menorrhagia. In one small study, 88% of women with menorrhagia improved when given 200 mg vitamin C and 200 mg flavonoids three times per day.1 In another study, 70% of women with excessive menstrual bleeding experienced at least a 50% reduction in bleeding after taking a flavonoid product.2 The preparation used in this study contained 90% diosmin and 10% hesperidin and was given in the amount of 1,000 mg per day, beginning five days prior to the expected start of menstruation and continuing until the end of bleeding for three cycles.

Dose: Refer to label instructionsVitamin C alone, at 400 mg daily, had no effect on amenorrhea in one preliminary trial, although it was associated with the return of ovulation in some women who were menstruating regularly but not ovulating. In a second phase of the trial, the same amount of vitamin C was combined with a drug that affects female hormone levels, and this combination was associated with return of ovulation in almost half of amenorrheic women who had not benefited from the drug alone.1 More studies of the effect of vitamin C on amenorrhea are needed.

Several studies have shown that supplementing with vitamin C can significantly reduce elevated intraocular pressure in individuals with glaucoma.1 These studies used at least 2 grams per day of vitamin C; much larger amounts were sometimes given. Higher quantities of vitamin C appeared to be more effective than smaller amounts.

Doctors often suggest that people with glaucoma take vitamin C to "bowel tolerance."2 The bowel-tolerance level is determined by progressively increasing vitamin C intake until loose stools or abdominal pain occurs, and then reducing the amount slightly, to a level that does not cause these symptoms. The bowel tolerance level varies considerably from person to person, usually ranging from about 5 to 20 or more grams per day. Vitamin C does not cure glaucoma and must be used continually to maintain a reduction in intraocular pressure.

Sunlight triggers oxidative damage in the eye, which in turn can cause macular degeneration.1 Because vitamin C functions as an antioxidant, it has the potential to protect against macular degeneration. However, in a double-blind trial, supplementing with 500 mg of vitamin C daily for eight years did not decrease the incidence of macular degeneration in healthy male physicians.2

People with low blood levels of antioxidants and those who eat few antioxidant-rich fruits and vegetables have been reported to be at high risk for cataracts.1, 2

The major antioxidants in the lens of the eye are vitamin C3 and glutathione (a molecule composed of three amino acids).4 Vitamin C is needed to activate vitamin E,5 which in turn activates glutathione. Both nutrients are important for healthy vision. People who take multivitamins or any supplements containing vitamins C or E for more than 10 years have been reported to have a 60% lower risk of forming a cataract.6

Vitamin C levels in the eye decrease with age.7 However, supplementing with vitamin C prevents this decrease8 and has been linked to a lower risk of developing cataracts.9, 10 Healthy people are more likely to take vitamin C and vitamin E supplements than those with cataracts according to some,11 but not all,12 studies. Dietary vitamin C intake has not been consistently associated with protection from cataracts.13, 14 Nonetheless, because people who supplement with vitamin C have developed far fewer cataracts in some research,15, 16 doctors often recommend 500 to 1,000 mg of vitamin C supplementation as part of a cataract prevention program. The difference between successful and unsuccessful trials may be tied to the length of time people actually supplement with vitamin C. In one preliminary study, people taking vitamin C for at least ten years showed a dramatic reduction in cataract risk, but those taking vitamin C for less than ten years showed no evidence of protection at all.17

As with vitamin E, vitamin C may reduce glycosylation.1 Vitamin C also lowers sorbitol levels in people with diabetes.2 Sorbitol is a sugar that can accumulate inside the cells and damage the eyes, nerves, and kidneys of people with diabetes. Vitamin C may improve glucose tolerance in type 2 diabetes,3, 4, 5although not every study confirms this benefit.6 Vitamin C supplementation (500 mg twice a day for one year) has significantly reduced urinary protein loss in people with diabetes. Urinary protein loss (also called proteinuria) is associated with poor prognosis in diabetes.7 Many doctors suggest that people with diabetes supplement with 1 to 3 grams per day of vitamin C. Higher amounts could be problematic, however. In one person, 4.5 grams per day was reported to increase blood sugar levels.8

One study examined antioxidant supplement intake, including both vitamins E and C, and the incidence of diabetic retinopathy (damage to the eyes caused by diabetes).9 Surprisingly, people with extensive retinopathy had a greater likelihood of having taken vitamin C and vitamin E supplements. The outcome of this trial, however, does not fit with most other published data and might simply reflect the fact that sicker people are more likely to take supplements in hopes of getting better. For the present, most doctors remain relatively unconcerned about the outcome of this isolated report.

Dose: 540 mg dailyThere are few controlled trials of antioxidant supplementation to patients with pancreatitis. One small controlled study of acute pancreatitis patients found that sodium selenite at a dose of 50 micrograms (mcg) daily resulted in decreased levels of a marker of free radical activity, and no patient deaths occurred.1 In a small double-blind trial including recurrent acute and chronic pancreatitis patients, supplements providing daily doses of 600 mcg selenium, 9,000 IU beta-carotene, 540 mg vitamin C, 270 IU vitamin E, and 2,000 mg methionine significantly reduced pain, normalized several blood measure of antioxidant levels and free radical activity, and prevented acute recurrences of pancreatitis.2 These researches later reported that continuing antioxidant treatment in these patients for up to five years or more significantly reduced the total number of days spent in the hospital and resulted in 78% of patients becoming pain-free and 88% returning to work.3

People with type 1 diabetes appear to have low vitamin C levels.1 As with vitamin E, vitamin C may reduce glycosylation.2 Vitamin C also lowers sorbitol levels in people with diabetes.3 Sorbitol is a sugar that can accumulate inside the cells and damage the eyes, nerves, and kidneys of people with diabetes. Vitamin C supplementation (500 mg twice a day for one year) has significantly reduced urinary protein loss in people with diabetes. Urinary protein loss (also called proteinuria) is associated with poor prognosis in diabetes.4 Many doctors suggest that people with diabetes supplement with 1 to 3 grams per day of vitamin C. Higher amounts could be problematic, however. In one person, 4.5 grams per day was reported to increase blood sugar levels.5

One study examined antioxidant supplement intake, including both vitamins E and C, and the incidence of diabetic eye damage (retinopathy).6 A surprising finding was that people with extensive retinopathy had a greater likelihood of having taken vitamin C and vitamin E supplements. The outcome of this study, however, does not fit with most other published data and might simply reflect the fact that sicker people are more likely to take supplements in hopes of getting better. For the present, most doctors remain relatively unconcerned about the outcome of this isolated report.

Research has shown that supplementing with chromium (200 mcg per day)1 or magnesium (340 mg per day)2 can prevent blood sugar levels from falling excessively in people with hypoglycemia. Niacinamide (vitamin B3) has also been found to be helpful for hypoglycemic people.3 Other nutrients, including vitamin C, vitamin E, zinc, copper, manganese, and vitamin B6, may help control blood sugar levels in diabetics.4 Since there are similarities in the way the body regulates high and low blood sugar levels, these nutrients might be helpful for hypoglycemia as well, although the amounts needed for that purpose are not known.

Dose: Refer to label instructionsBecause oxidation damage is believed to play a role in the development of diabetic eye damage (retinopathy), antioxidant nutrients might be protective. One doctor has administered a daily regimen of 500 mcg selenium, 800 IU vitamin E, 10,000 IU vitamin A, and 1,000 mg vitamin C for several years to 20 people with diabetic eye damage (retinopathy). During that time, 19 of the 20 people showed either improvement or no progression of their retinopathy.1 People who wish to supplement with more than 250 mcg of selenium per day should consult a healthcare practitioner.

Dose: Refer to label instructionsBecause oxidation damage is believed to play a role in the development of diabetic eye damage (retinopathy), antioxidant nutrients might be protective. One doctor has administered a daily regimen of 500 mcg selenium, 800 IU vitamin E, 10,000 IU vitamin A, and 1,000 mg vitamin C for several years to 20 people with diabetic eye damage (retinopathy). During that time, 19 of the 20 people showed either improvement or no progression of their retinopathy.1 People who wish to supplement with more than 250 mcg of selenium per day should consult a healthcare practitioner.

Dose: 200 mg niacin daily, 300 mg vitamin C daily, and 60 mg rutin daily througout menstrual cycle; for cramps: 100 mg niacin every two to three hoursThe niacin form of vitamin B3 has been reported to be effective in relieving menstrual cramps in 87% of a group of women taking 200 mg of niacin per day throughout the menstrual cycle.1 They then took 100 mg every two or three hours while experiencing menstrual cramps.2 In a follow-up study, this protocol was combined with 300 mg of vitamin C and 60 mg of the flavonoid rutin per day, which resulted in a 90% effectiveness for relieving menstrual cramps. Since these two preliminary studies were published many years ago, no further research has explored the relationship between niacin and dysmenorrhea. Niacin may not be effective unless taken for seven to ten days before the onset of menstrual flow.

Dose: 1,000 mg vitamin C and 1,200 IU vitamin E dailyIn a double-blind study of women with pelvic pain presumed to be due to endometriosis, supplementation with vitamin E (1,200 IU per day) and vitamin C (1,000 mg per day) for eight weeks resulted in an improvement of pain in 43% of women, whereas none of the women receiving a placebo reported pain relief.1

Both vitamin C and flavonoids protect capillaries (small blood vessels) from damage. In so doing, they might protect against the blood loss of menorrhagia. In one small study, 88% of women with menorrhagia improved when given 200 mg vitamin C and 200 mg flavonoids three times per day.1 In another study, 70% of women with excessive menstrual bleeding experienced at least a 50% reduction in bleeding after taking a flavonoid product.2 The preparation used in this study contained 90% diosmin and 10% hesperidin and was given in the amount of 1,000 mg per day, beginning five days prior to the expected start of menstruation and continuing until the end of bleeding for three cycles.

Dose: Refer to label instructionsVitamin C alone, at 400 mg daily, had no effect on amenorrhea in one preliminary trial, although it was associated with the return of ovulation in some women who were menstruating regularly but not ovulating. In a second phase of the trial, the same amount of vitamin C was combined with a drug that affects female hormone levels, and this combination was associated with return of ovulation in almost half of amenorrheic women who had not benefited from the drug alone.1 More studies of the effect of vitamin C on amenorrhea are needed.

Supplementation with 1 gram of vitamin C per day reduces the tendency of the bronchial passages to go into spasm,1 an action that has been confirmed in double-blind research.2 Beneficial effects of short-term vitamin C supplementation (i.e., less than three days) have been observed. In double-blind trials, supplementation with 1,000 to 1,500 mg of vitamin C per day for 2 to 14 days prevented attacks of exercise-induced asthma.3, 4 Two other preliminary trials found that vitamin C supplementation reduced bronchial reactivity to metacholine, a drug that causes bronchial constriction.5, 6 However, other studies,7 including two double-blind trials,8, 9 have failed to corroborate these findings. The only double-blind trial of a long duration found that vitamin C supplementation (1 gram per day for 14 weeks) reduced the severity and frequency of attacks among Nigerian adults with asthma.10 A buffered form of vitamin C (such as sodium ascorbate or calcium ascorbate) may work better for some asthmatics than regular vitamin C (ascorbic acid).11

Although vitamin C has antihistamine activity, and supplementation, in preliminary research,1, 2 has been reported to help people with hay fever, 2,000 mg of vitamin C per day did not reduce hay fever symptoms in a placebo controlled trial.3 Thus, while some doctors recommend that hay fever sufferers take 1,000-3,000 mg of vitamin C per day, supportive evidence remains weak.

In theory, high amounts of vitamin C might help people with hives by lowering histamine levels.1 Amounts of at least 2,000 mg daily appear necessary to produce these effects.2 No research trials have yet explored the clinical effects of vitamin C supplementation in people with hives.

There is some evidence that combinations of antioxidants such as vitamin E, vitamin C, and selenium may help improve symptoms of asthma throught to be caused by air pollution.1 In one double-blind study, 46 Dutch bicyclists were randomly assigned to receive a placebo or 100 mg of vitamin E and 500 mg of vitamin C daily for 15 weeks.2 Lung function was measured before and after each training session on 380 different occasions, and ambient ozone concentrations were measured during each training session. After analysis, researchers concluded that bicyclists with the vitamins C and E blunted the adverse effects of ozone on measures of lung function. In another double-blind study, 17 adults (18 to 39 years old) were randomly assigned to receive either 400 IU per day of vitamin E and 500 mg per day of vitamin C or a placebo for five weeks.3 Tests showing improved measures of lung function led researchers to conclude that supplementation with vitamins C and E inhibited the decline in pulmonary function induced in asthmatics by exposure to air pollutants. Also using a double-blind design, another study of 158 children with asthma living in Mexico City were randomly assigned to receive, a daily supplement containing 50 mg of vitamin E and 250 mg of vitamin C or a placebo.4 Tests results suggested that supplementing with vitamins C and E may reduce the adverse effect of ozone exposure on lung function of children with moderate to severe asthma.

When H. pylori causes gastritis, free radical levels rise in the stomach lining.1 These unstable molecules contribute to inflammation and damage to the stomach lining. Vitamin C, an antioxidant that helps quench free radical molecules, is low in the stomach juice of people with chronic gastritis. This deficiency may be the link between chronic gastritis and the increased risk of stomach cancer. When people with gastritis took 500 mg of vitamin C twice a day, vitamin C levels in their gastric juice rose, though not to normal levels.2 In another trial, vitamin C supplementation (5 grams per day divided into several doses for four weeks) appeared to eliminate H. pylori infection.3 While no direct evidence proves that taking vitamin C reduces gastritis symptoms, scientists widely believe that any agent capable of knocking out H. pylori should help people with this condition.

Little is known about the effects of vitamin C supplementation for people with peptic ulcer. People with gastritis, a related condition, have been found to have low levels of vitamin C in their stomach juice. Vitamin C may also help eradicate H. pylori in people with gastritis. Vitamin C may one day prove to have a therapeutic effect for people with peptic ulcer; however, further research in this area is needed.1

Vitamin C is needed to convert cholesterol to bile acids. In theory, such a conversion should reduce gallstone risks. Women who have higher blood levels of vitamin C have a reduced risk of gallstones.1 Although this does not prove that vitamin C supplements can prevent or treat gallstones, some researchers believe this is plausible.2 One study reported that people who drink alcohol and take vitamin C supplements have only half the risk of gallstones compared with other drinkers, though the apparent protective effect of vitamin C did not appear in non-drinkers.3 In another trial, supplementation with vitamin C (500 mg taken four times per day for two weeks before gallbladder surgery) led to improvement in one parameter of gallstone risk ("nucleation time"), though there was no change in the relative level of cholesterol found in bile.4 While many doctors recommend vitamin C supplementation to people with a history of gallstones, supportive evidence remains preliminary.

Vitamin K and vitamin C, taken together, may provide relief of symptoms for some women. In one study, 91% of women who took 5 mg of vitamin K and 25 mg of vitamin C per day reported the complete disappearance of morning sickness within three days.1 Menadione was removed from the market a number of years ago because of concerns about potential toxicity. Although some doctors still use a combination of vitamin K1 (the most prevalent form of vitamin K in food) and vitamin C for morning sickness, no studies on this treatment have been done.

In one small study, people who took 4 grams of vitamin C (but not lower amounts) had an increase in urinary excretion of uric acid within a few hours, and those who took 8 grams of vitamin C per day for several days had a reduction in serum uric acid levels.1 Thus, supplemental vitamin C could, in theory, reduce the risk of gout attacks. However, the authors of this study warned that taking large amounts of vitamin C could also trigger an acute attack of gout by abruptly changing uric acid levels in the body. Another study showed that taking lower amounts of vitamin C (500 mg per day) for two months significantly reduced blood levels of uric acid, especially in people whose initial uric acid levels were elevated.2 For people with a history of gout attacks, it seems reasonable to begin vitamin C supplementation at 500 mg per day, and to increase the amount gradually if uric acid levels do not decrease.

A preliminary report in 1964 suggested that 500-1,000 mg per day of vitamin C helped many people avoid surgery for their disc-related low back pain.1 No controlled research has been done to examine this claim further.

Many doctors recommend 5,000 mg or more of vitamin C per day for an acute UTI, as well as long-term supplementation for people who are prone to recurrent UTIs. Vitamin C has been shown to inhibit the growth of E. coli, the most common bacterial cause of UTIs.1 In addition, supplementation with 4,000 mg or more of vitamin C per day, results in a slight increase in the acidity of the urine,2 creating an "unfriendly" environment for some infection-causing bacteria. In one controlled trial, pregnant women who supplemented with 100 mg of vitamin C per day experienced 56% less UTI frequency, compared with a placebo.3

Premature rupture of membranes (PROM) affects 10 to 20% of all pregnancies. It is an important cause of preterm delivery and is associated with increased rates of complications in both the mother and child. In a double-blind study, supplementing with 100 mg of vitamin C per day, beginning in the twentieth week of pregnancy, reduced the incidence of PROM by 74%.1 The women in this study were consuming only about 65 mg of vitamin C per day in their diet, which is less than the RDA of 80 to 85 mg per day for pregnant women. In a double-blind study of pregnant smokers, supplementation with 500 mg per day of vitamin C, beginning at 23 weeks of pregnancy or earlier and continuing until delivery, improved lung function and decreased the incidence of wheezing in the offspring.2

In one double-blind trial lasting ten weeks, autistic children given 1 gram vitamin C per day for each 20 pounds of body weight showed a reduction in symptom severity compared with placebo.1 The authors speculate that vitamin C may play a positive role because of its known effects on a hormone pathway typically disturbed in children with autism.

Vitamin C has been demonstrated in test tube, animal, and human studies to have immune-enhancing and direct antiviral properties.1 Preliminary observations made on the effect of vitamin C on viral infections have involved both measles and chicken pox.2 An active immune system uses vitamin C rapidly, and blood levels fall in children with bacterial or viral infections.3 Reduced immune cell activity has been observed in people with measles, but in one preliminary study, supplementation with 250 mg daily of vitamin C in children 18 months to 3 years old had no impact on the course of the illness.4 The authors of this study admit that this amount of vitamin C may have been too low to bring about an observable increase in immune cell activity and thus an increase in speed of recovery.

Vitamin C supplementation has been reported to stimulate immune function.1, 2 As a result, some doctors recommend between 500 mg and 1,000 mg of vitamin C per day for people with ear infections. Nonetheless, vitamin C supplementation has not been studied by itself in people with ear infections.

In 1964, a preliminary trial reported that 1,200 mg each of vitamin C and the flavonoid hesperidin taken over the course of the day helped relieve hot flashes.1 Although placebo effects are strong in women with hot flashes, other treatments used in that trial failed to act as effectively as the flavonoid/vitamin C combination. Since then, researchers have not explored the effects of flavonoids or vitamin C in women with menopausal symptoms.

Vitamin C supplementation has been reported to stimulate immune function.1, 2 As a result, some doctors recommend between 500 mg and 1,000 mg of vitamin C per day for people with ear infections. Nonetheless, vitamin C supplementation has not been studied by itself in people with ear infections.

Up to 6 grams daily of vitamin C has been reported to be beneficial for people with schizophrenia;1, 2 in one case the addition of 400 IU daily of vitamin E enhanced this benefit.3 A small preliminary trial using 8 grams daily of vitamin C showed decreases in hallucinations, suspiciousness, and unusual and disorganized thoughts in 77% of schizophrenic patients.4 In all reported cases, patients were also being treated with sychiatric medications. Some early studies found no difference between blood and urine vitamin C levels in schizophrenics and non-schizophrenics, either before or after supplementation.5, 6, 7 However, later studies found that blood and urine levels of vitamin C were lower in schizophrenics than in non-schizophrenics before and after a single 1,000 mg "load" of vitamin C was taken. After four weeks of daily supplementation with 1,000 mg of vitamin C, blood levels became the same, but urinary levels remained lower in the schizophrenic group, leading the researchers to conclude that the amount of vitamin C required by people with schizophrenia may be greater than that of the general population.8, 9

Use of vitamin C or vitamin E supplements, or both, has been associated with better cognitive function and a reduced risk of certain forms of dementia (not including Alzheimer's disease).1 Clinical trials of these antioxidants are needed to confirm the possible benefits suggested by this study.

Vitamin C helps the body to reduce its load of vanadium and this has been studied for its possible role in treatment of bipolar disorder.1 A double-blind trial found that both manic and depressed bipolar patients were significantly improved after one-time administration of 3 grams of vitamin C, compared with a placebo.2 The same study found that both manic and depressed patients did better on a reduced-vanadium diet compared to a normal diet. Another double-blind study reported that 4 grams per day of vitamin C in combination with a drug known as EDTA (which also helps remove elements such as vanadium from the body) was helpful to depressed bipolar patients but not to those experiencing mania.3 Until more is known, people with bipolar illness should avoid supplements containing vanadium and consider supplementing with vitamin C.

Most research has demonstrated that strenuous exercise increases production of harmful substances called free radicals, which can damage muscle tissue and result in inflammation and muscle soreness. Exercising in cities or smoggy areas also increases exposure to free radicals. Antioxidants, including vitamin C and vitamin E, neutralize free radicals before they can damage the body, so antioxidants may aid in exercise recovery. Regular exercise increases the efficiency of the antioxidant defense system, potentially reducing the amount of supplemental antioxidants that might otherwise be needed for protection. However, at least theoretically, supplements of antioxidant vitamins may be beneficial for older or untrained people or athletes who are undertaking an especially vigorous training protocol or athletic event.1, 2

Placebo-controlled research, some of it double-blind, has shown that taking 400 to 3,000 mg of vitamin C per day for several days before and after intense exercise may reduce pain and speed up muscle strength recovery.3, 4, 5 However, taking vitamin C only after such exercise was not effective in another double-blind study.6 While some research has reported that vitamin E supplementation in the amount of 800 to 1,200 IU per day reduces biochemical measures of free radical activity and muscle damage caused by strenuous exercise,7, 8, 9 several studies have not found such benefits,10, 11, 12, 13 and no research has investigated the effect of vitamin E on performance-related measures of strenuous exercise recovery. A combination of 90 mg per day of coenzyme Q10 and a very small amount of vitamin E did not produce any protective effects for marathon runners in one double-blind trial,14 while in another double-blind trial a combination of 50 mg per day of zinc and 3 mg per day of copper significantly reduced evidence of post-exercise free radical activity.15

In most well-controlled studies, exercise performance has not been shown to improve following supplementation with vitamin C, unless a deficiency exists, as might occur in athletes with unhealthy or irrational eating patterns.16, 17 Similarly, vitamin E has not benefited exercise performance, 18, 19 except possibly at high altitudes. 20, 21

Most research has demonstrated that strenuous exercise increases production of harmful substances called free radicals, which can damage muscle tissue and result in inflammation and muscle soreness. Exercising in cities or smoggy areas also increases exposure to free radicals. Antioxidants, including vitamin C and vitamin E, neutralize free radicals before they can damage the body, so antioxidants may aid in exercise recovery. Regular exercise increases the efficiency of the antioxidant defense system, potentially reducing the amount of supplemental antioxidants that might otherwise be needed for protection. However, at least theoretically, supplements of antioxidant vitamins may be beneficial for older or untrained people or athletes who are undertaking an especially vigorous training protocol or athletic event.1, 2

Placebo-controlled research, some of it double-blind, has shown that taking 400 to 3,000 mg of vitamin C per day for several days before and after intense exercise may reduce pain and speed up muscle strength recovery.3, 4, 5 However, taking vitamin C only after such exercise was not effective in another double-blind study.6 While some research has reported that vitamin E supplementation in the amount of 800 to 1,200 IU per day reduces biochemical measures of free radical activity and muscle damage caused by strenuous exercise,7, 8, 9 several studies have not found such benefits,10, 11, 12, 13 and no research has investigated the effect of vitamin E on performance-related measures of strenuous exercise recovery. A combination of 90 mg per day of coenzyme Q10 and a very small amount of vitamin E did not produce any protective effects for marathon runners in one double-blind trial,14 while in another double-blind trial a combination of 50 mg per day of zinc and 3 mg per day of copper significantly reduced evidence of post-exercise free radical activity.15

In most well-controlled studies, exercise performance has not been shown to improve following supplementation with vitamin C, unless a deficiency exists, as might occur in athletes with unhealthy or irrational eating patterns.16, 17, 18 Similarly, vitamin E has not benefited exercise performance, 19, 20 except possibly at high altitudes. 21, 22

Most research has demonstrated that strenuous exercise increases production of harmful substances called free radicals, which can damage muscle tissue and result in inflammation and muscle soreness. Exercising in cities or smoggy areas also increases exposure to free radicals. Antioxidants, including vitamin C and vitamin E, neutralize free radicals before they can damage the body, so antioxidants may aid in exercise recovery. Regular exercise increases the efficiency of the antioxidant defense system, potentially reducing the amount of supplemental antioxidants that might otherwise be needed for protection. However, at least theoretically, supplements of antioxidant vitamins may be beneficial for older or untrained people or athletes who are undertaking an especially vigorous training protocol or athletic event.1, 2

Placebo-controlled research, some of it double-blind, has shown that taking 400 to 3,000 mg of vitamin C per day for several days before and after intense exercise may reduce pain and speed up muscle strength recovery.3, 4, 5 However, taking vitamin C only after such exercise was not effective in another double-blind study.6 While some research has reported that vitamin E supplementation in the amount of 800 to 1,200 IU per day reduces biochemical measures of free radical activity and muscle damage caused by strenuous exercise,7, 8, 9 several studies have not found such benefits,10, 11, 12, 13 and no research has investigated the effect of vitamin E on performance-related measures of strenuous exercise recovery. A combination of 90 mg per day of coenzyme Q10 and a very small amount of vitamin E did not produce any protective effects for marathon runners in one double-blind trial,14 while in another double-blind trial a combination of 50 mg per day of zinc and 3 mg per day of copper significantly reduced evidence of post-exercise free radical activity.15

In most well-controlled studies, exercise performance has not been shown to improve following supplementation with vitamin C, unless a deficiency exists, as might occur in athletes with unhealthy or irrational eating patterns.16, 17 Similarly, vitamin E has not benefited exercise performance, 18, 19 except possibly at high altitudes. 20, 21

Vitamin C protects sperm from oxidative damage.1 Supplementing vitamin C improves the quality of sperm in smokers.2 When sperm stick together (a condition called agglutination), fertility is reduced. Vitamin C reduces sperm agglutination,3 and supplementation with 200-1,000 mg per day increased the fertility of men with this condition in a controlled study.4, 5 Many doctors recommend 1 gram of vitamin C per day for infertile men, particularly those diagnosed with sperm agglutination. However, a double-blind trial studying the effects of combined vitamin C and vitamin E supplementation found no improvements in semen quality among men with low sperm motility.6

The information presented by Healthnotes is for informational purposes only. It is based on scientific studies (human, animal, or in vitro), clinical experience, or traditional usage as cited in each article. The results reported may not necessarily occur in all individuals. Self-treatment is not recommended for life-threatening conditions that require medical treatment under a doctor's care. For many of the conditions discussed, treatment with prescription or over the counter medication is also available. Consult your doctor, practitioner, and/or pharmacist for any health problem and before using any supplements or before making any changes in prescribed medications. Information expires June 2017.